Erosion and tectonic activity through geological-time may transform an initially uniform stratified terrain composed of a continuous stack of depositional surfaces, called horizons, into a faulted and folded terrain fractured by faults forming discontinuities across the originally continuous horizons. Accordingly, to model the structures at their predicted or simulated original time of deposition from data collected from the current subsurface structures (e.g., to “reverse time”), the model may simulate a reversal of such erosion and tectonic activity.
A particle of sediment observed today at geographical coordinates (x,y) and altitude or vertical component (z) may have been deposited at an original time of deposition or “geological-time” t(x,y,z) at paleo-geographical coordinates u(x,y,z) and v(x,y,z). Depositional coordinates (u,v,t) so defined may be different than the observed (present day's) geographic coordinates (x,y,z). The “GeoChron” model may provide systems and methods to calculate or predict the depositional (past) coordinates u(x,y,z), v(x,y,z) and t(x,y,z) of a particle of sediment in a subsurface structure from its observed (present day) coordinates (x,y,z) in the geological layers. The depositional coordinates (u,v,t) may be displayed to model a simulation of the subsurface structures as they are predicted to have appeared at their original time of deposition.
Depending on the paleo-environment prevailing at the geological time of deposition, particles of sediment may have been deposited according to different depositional styles (such as, for example, on-lap, off-lap, or proportional) which may have impacted the geometry of the layers.
For more than three decades, geologists and geophysicists in the water, mineral (e.g. mining) and energy (e.g. oil and gas) industries have modelled “attributes” to characterize the properties of sedimentary terrains in the subsurface. An attribute may be a function f(x,y,z) which, based on observed data, such as seismic data or well data, may be estimated at each location (x,y,z) or coordinate in the present-day subsurface. The functions may statistically correlate with rock types and properties of the terrains and the functions may be used to identify these properties in a current time or predict these properties at a time of original deposition. These properties may be related to two previously known families of attributes, seismic attributes and geometric attributes:                Seismic attributes may be defined based on the shape of an observed seismic signal reflected by geological structures in the subsurface. The observed seismic signal may be recorded by a seismograph when measuring ground movement. Frequently used seismic attributes may include, for example, “instantaneous amplitude,” “instantaneous velocity.” and “instantaneous acceleration.” These attributes may be computed using first and second order derivatives of the observed seismic signal crossing the geologic layers.        Geometrical attributes may be defined based on the shape of geological horizons or surfaces bounding geological layers and may provide information about the curvatures and distances to faults. Frequently used geometrical attributes may include “Gaussian curvature,” “mean curvature,” and “main curvature.” These attributes may be computed using first and second order derivatives of a parametric representation of the horizons bounding the geologic layers.        